Narrated Abu Huraira
Allah's Messenger (ﷺ) said, "Do you consider or see that my face is towards the Qibla? By Allah, neither your submissiveness nor your bowing is hidden from me, surely I see you from my back."
Narrated Anas bin Malik
The Prophet (ﷺ) led us in a prayer and then got up on the pulpit and said, "In your prayer and bowing, I certainly see you from my back as I see you (while looking at you.)"